Refrigeration



M y 1940- H. ULLSTRAND BEFRIGE RATION Filed April '7, 1938 2Sheets-Sheet l INVENTOR Ale ATTORNEY.

y 28, 1940- H. M. ULLSTRAND 2,202,360

REFRIGERATION Filed- April '7, 1938 2 Sheets-Sheet 2 6 INVENTOR.

A44 ATTORNEY.

and therebetween. '45 Thgabsorber I3 is cooled'by a 'vaporizationasuitable heat transfer fluid and comprises a Patented May 28, 1940 l vUNITED STATES PATENT OFFICE REFRIGERATION Hugo M. Ullstrand, Evansville,Ind., assignor to Servcl, Inc., New York, N. Y., a corporation ofDelaware Application April 7, 1938, Serial No. 200,568

' 11 Claims. (Cl. 62-4195) My invention relates to a method andapparatus from solution by heating in the generator [0. for heattransfer by fluid and more particularly Ammonia vapor is condensed toliquid in the conto heat transfer by fluid for removal of frost denserll.- Liquid ammonia evaporates and from a refrigerator cooling surface.diffuses into hydrogen in the evaporator [2 pro- It is an object of theinvention to provide a ducing a refrigerating effect. Ammonia vapor 5self-stopping fluid heat transfer system. It is is absorbed out of thegas into solution in the another object to remove frost quickly. Anotherabsorber l3. Heat input at the generator l object is to provide aself-stopping method an and evaporator I2 is dissipated from the con--apparatus for frost removal. densers II and 23. The generator heatingburner 10 I utilize vaporization and condensation offluid l may beautomatically controlled by a thermoto heat frost to cause it to meltand drain from static device (not shown) responsive to temperaa coolingsurface and cause cessation of heating ture of the evaporator l2. I bystoppage of liquid fiow as more fully set forth The evaporator l2, asbetter shown in Fig. 2, in the following description in connection withcomprises a pipe coil-25 in a cast aluminum shell the accompanyingdrawings, of which: 26. The evaporator is constructed to receive 15 Fig.1 shows a heat operated refrigeration ice freezing trays or the like(not shown) on its system embodying the invention; shelves 2! and isarranged in the upper part of Fig. 2 is a sectional view on line 22 inFig. 1; the storage compartment '20 for cooling of air in .Fig. 3 is adetail section of a valve shown in this compartment by natural draftcirculation. Fig. 1; and v Whenthe system is operated so that the evapo-20 Fig. 4 illustrates a heat operated refrigeration rator I2 isattemperatures below the freezing system embodying a modification of theinvenpoint of water, as is necessary to produce ice tion. freezing,frost forms on the surfaces I of the Referring to Fig.1, therefrigeration system evaporator due'to condensation of water vaporincludes a generator II], a condenser ll, an from air flowing in contactwith these surfaces, 25

evaporator l2, and an absorber I3. The generator and freezing of thecondensate.

In is provided with a flue l4 and is heated by a It is desirabletoremove this frost at intervals burner l5 arranged so that the flame isproboth on account of its thermal insulating property jected into thelower end of the flue. The generaand also for sanitary reasons. Toprovide for retor l0 and absorber l3 .are interconnected by moval of thefrost, I'provide pipe coils 28 and 30 members including a liquid heatexchanger I6 29 which are flat and strapped against each side forcirculation of absorption liquid therethrough of the evaporator casing26. The lower ends of and therebetween. Circulation 'of the absorptioncoils 28 and 29' are connected to a receiver 3!) liquid is caused by avapor lift conduit II. The located beneath the evaporator. Theupper'ends 36 generator I0 is connected by a conduit I 8' for of thecoils 28 and 29 are connected together and delivery of vapor to thecondenser II. The conboth connected by a conduit 3| to the upper partdenser is connected by a. conduit l9 to the evapoof a jacket 32 locatedaround the-generator flue 'rator l2for flow of liquid fromthecondenserto the The lower part of the jacket 32 is connected evaporator. Theevaporator I2 is located in the by a conduit 33 to the receiver 30. Inthe con- 40' upperpartofarefrigeratorstoragecompartment. duit 33 is avalve 3|. The jacket islocated 0 z The evaporator I 2 and absorber l3are interconat a point lower than the evaporator so thatv e t by membersincluding a, gas h at xliquid will flow from receiver-30 through conduiti changer 2| for circulation of gas therethrough 33 into the jacket 32.The circuit formed'by the parallel coils 28, 29 and the jacket 32 isfilled with condensation ci it including a i 2: avaporization-condensation circuit of which the ranged in contact withthe absorber and conj ke 2 is e ac of vapo i io a th nected to an aircooled condenser 23. I coils 28. 29 are the place of condensation. The

The lower end of condenser'll is connected to quantity 1' fl P ced nthis circu t S o d be the gas heat exchanger 2| by conduitsincludsufficient that when it is substantially all in liquid 50 ing agas accumulation vessel 24. p e it will be held by thereceiver, 30 andcoils The system contains refrigerant fluid, a liquid 28, absorbenttherefor, and inert gas. Thesefluids Thevalve 34 is a normally closedvalve. Itis may be, for instance, ammonia, water, and hydroshown indetail section in Fig. 3. I The valve 34 gen, respectively. Ammoniavapor is distilled comprises a casing 35 and a can 36. Th asin providesa fluid passage in which there is a valve opening 31. The valve opening31 is controlled by a valve member 38. The valve member 38 is mounted ona diaphragm 39 which is secured at its periphery between ledges on thevalve casing 35 and the cap 38. The ends of the fluid passage in casing35 are constructed for connection thereto of the pipes forming conduit33. On the cap 36 there is pivoted a lever 48 which has a short arm anda long arm respectively on opposite sides of the pivot. The valve member38 is secured in the center of a diaphragm 39 in a manner so that itextends through the diaphragm. On the outside of the diaphragm a screwis secured to the valve member 38. This screw has a large flat head 4|.The lever is arranged so that the short arm is held against the screw.head 41 by the weight of the longer arm. The described parts aredimensioned so that when the valve 38 is closed, the lever 48 hangs in avertical position and locks the valve closed.

The diaphragm 39 is a metal disc which is formed so-that its center isnormally flexed upward, in which position the valve 38 is closed. Thediaphragm 39 is a resilient over-center snapaction disc which isunstable when its center is flexed downward.

In operation, assume that valve member 38 is closed and lever 40 hangsvertically as illustrated in Fig. 1. The receiver 38 and coils 28 and 29are flooded with liquid. The weight of the liquid is exerted downward ondiaphragm 39 which, however, cannot move downward under this weightbecause it is locked by lever 48. It is now desired to remove thecoating of frost which has formed on the surface of the refrigeratorcooling element I2 and the coils 28 and 29 which are attached thereto.By pushing on the lower end of lever 48, the upper end of this lever isdisplaced from beneath the center of the flat headed screw 4|. Theweight of liquid above diaphragm 39 causes the diaphragm to snapdownward. This opens valve member 38, permitting liquid to drain fromreceiver 38 through conduit 33 into jacket 32. As liquid drains into thejacket, the height of liquid above the diaphragm 39 decreases. When theliquid level reaches the bottom of receiver 38, the weight of liquid isnot sufficient to overcome the internal stress in diaphragm 39 whichthen snaps upward and closes valve member 38. Thus the valve acts as ametering device which measures a predetermined quantity of liquid intothe vaporizing jacket. When diaphragm 39 snaps upward, the lever 48resumes its vertical position in which the valve member 38 is locked inits closed position.

Liquid is vaporized in jacket 32 by heat from the flue 14. The vaporflows through conduit 3| into coils 28 and 29. The vapor condenses inthe coils 28 and 29 and flows downward into receiver 38. This continuesuntil all of the liquid has been boiled out of jacket 32 and the coils28 and 29 and receiver 30 are again flooded with liquid. The heat ofcondensation of vapor in coils 28 and 29 is transferred to the frost tosupply heat of fusion thereto so that the frost melts and runs off thesurfaces of the cooling element.

The quantity'of liquid in the frost melting system should 'be suflicientto carry out the transfer of the necessary quantity of heat to melt theing system becomes inactive until again set into operation bymanipulation of lever 48.

A frost melting system like that just described may be used to transferheat from any suitable source. Other parts ofthe refrigeration systemmay supply the heat. Heat from the absorber, for instance, may be used.This is illustrated in Fig. 4. All the parts shown in Fig. 4 are thesame as those shown in Fig. 1 and indicated by the same referencenumerals. In this modification, however, the flue jacket 32 iseliminated and conduits 3| and 33 are connected respectively to theconduits connecting the upper and lower ends of the absorber coolingcoil 22 and the condenser 23. This connection places the frost meltingcoils 28 and 29 in parallel with the absorber cooling condenser 23. Inthis arrangement, the same fluid is used in the absorber cooling circuitand the frost melting circuit. The quantity of fluid in the system isthe sum of that required for the absorber cooling and frost meltingparts. When valve 34 is operated, as previously described, liquid fromreceiver 38 and coils 28 and 29 is dumped into the absorber coolingcircuit. To accommodate this extra quantity of liquid, a receiver, notshown, could be connected to the absorber cooling circuit if foundnecessary.

When liquid has been dumped from coils 28 and 29 and receiver 38 bymanipulation of valve 34, vapor from the absorber cooling coil 22 alsoenters coils 28 and 29. This continues, causing melting of frost aspreviously described, until the coils 28 and 29 are again fllled withliquid.

Various changes and modifications may be made within the scope of theinvention which is set forth in the following claims.

What is claimed is:

1. The combination with a refrigeration system having a cooling elementsubject to formation of frost thereon, of a vaporization-condensationcircuit forming a heater for melting the frost, a device for stoppingand starting circulation of fluid in said circuit, means for operatingsaid device to start circulation and stop circulation responsive tochange in quantity of fluid in liquid phase in a part of said circuit.

2. In a refrigerator having cooling surfaces subject to formation offrost thereon, a heater for melting the frost including avaporizationcondensation heat transfer circuit, means for admittingliquid to the vaporization portion of said circuit, and means forterminating operation of said first means responsive to decrease inquantity of liquid in a part of said'circuit caused by operation of saidfirst means.

3. A method of melting frost from cooling surfaces of a refrigeratorwhich includes transferring heat to the frost with the aid of avaporization-condensation circuit, and terminating heat transfer byfilling the condensation portion of said circuit with liquid.

4. A method of melting frost on cooling surfaces of a refrigeratorwhichincludes transferring heat to the frost with the aid of avaporization-condensation circuit and admitting liquid only .inpredetermined quantities to the vaporization portion of said circuit.

'5. The combination with a refrigerator hav-- ing cooling surfacessubject to formation of frost thereon, of a vaporization-condensationcircuit for transferring heat to the frost to cause melting thereof, anda device for metering flow of fluid in said circuit.

6. A'method of melting frost on the cooling surfaces of a refrigeratorwhich includes measuring a quantity of liquid by weighing. vaporizingsaid quantity of liquid, and condensing the vapor in heating relation tothe frost.

7, In a refrigerator having cooling surfaces subject to formation offrost, a vaporization-condensation circuit for melting-the frost, meansfor flooding the condensation portion of said circuit with liquid toprevent heat transfer thereto and discharging liquid therefrom to permitheat transfer thereto.

8. The combination with a refrigeration system having cooling surfacessubject to formation of frost thereon and a vaporization-condensationheat transfer circuit cooling another part of the system, of a condenserconnected to said vaporization-condensation circuit and arranged to heatthe frost to cause melting thereof, and means for flooding saidcondenser with liquid to exclude vapor from said circuit and dischargeliquid therefrom to permit entrance of vapor from said circuit whendefrosting is desired.

9. An absorption refrigeration system including a cooling elementsubject to formation of frost thereon, an absorber, avaporization-condensation circuit for cooling said absorber and having aplurality of places of condensation one of which is arranged to heat thefrost to cause melting thereof, and means for controlling flow of heattransfer fluid in said one of the places of condensation.

10. In a refrigerator having cooling surfaces subject to formation offrost thereon, a heater for melting the frost including'avaporizationcondensation heat transfer circuit, and a self closing valvein said circuit in the path of flow of liquid between the condensationportion and the vaporization portion of the circuit.

11. A refrigerator as set forth in claim 10 in which there is areservoir for liquid in said path of flow between the condensationportion and said valve.

HUGO M. ULLS'I'RAND.

